SPID#: 70 Meibomian glands are sebaceous glands in the eyelids. They secrete a mixture of lipids and other components that form the outer layer of the tear film. This layer functions to decrease tear evaporation and surface tension of the tear film. The clinical importance of these secretions is evident from gland dysfunctions that can cause dry eye symptoms, keratoconjunctivitis, and cataract lens intolerance. Thus, a better understanding of the mechanisms that control meibomian gland secretion could be of importance in preventing some of these incapacitating and painful eye disorders. Meibomian glands receive significant innervations in rats, but information on primates is limited. To characterize the innervation of monkey meibomian glands, we were able to collect eyelids from monkeys that became available from other experiments. To localize and characterize nerves in meibomian glands, we used immunohistochemical staining for neuropeptides and neuronal enzymes, including NSE, TH, NPY, VIP, CGRP and SP. Antibodies to NSE, NPY and VIP revealed abundant nerve fibers closely opposed to the basement membrane of acini. Nerve fibers containing TH, CGRP, and SP were more sparse. Thus, primate meibomian glands are richly innervated by nerve fibers largely of parasympathetic origin and by a relatively smaller contribution from sympathetic and sensory sources. Based on the diversity of neurotransmitter- neuromodulator substances, meibomian gland secretion must be controlled by diverse mechanism. This project was partly supported by EY09737. Number of monkeys 7, they are the same used in eye growth experiments.